In recent years, light emitting devices or displays using light emitting elements made of organic materials have been actively developed. Among these, an organic electroluminescence (EL) device in which alight emitting layer made of an organic thin film, a hole transport layer, and an electron transport layer are laminated is a carrier injection-type self-light emitting device. The organic EL device is a promising display since a high luminance is obtained from this device.
As electron transporting materials or light emitting materials for the organic EL device, metal complexes having organic ligands (hereinafter, abbreviated to organometallic complexes) are being used. For example, if tris(8-hydroxyquinolinato)aluminum (Alq3) as an alumiquinolinium complex is vacuum-deposited between a hole transport layer and a cathode made of aluminum, the organic EL element can be prepared, and therefore, Alq3 is being used as an organometallic complex material having excellent electron transporting properties and light emitting properties.
Currently, as a method for forming a organometallic complex film, a dry process by vacuum deposition is mainly used. However, in view of simplicity of the production process, achievement of a large area, or the like, a wet process using polymer materials is also being examined (for example, see Non-Patent Literature 1).
In addition, in view of stabilizing organic EL characteristics, various organic-inorganic hybrid materials obtained by protecting organic light emitting materials with inorganic oxides such as silica have been proposed.
When a sol-gel method is used for synthesizing these organic-inorganic hybrid materials, light emitting hybrid materials synthesized at a relatively low temperature are obtained (for example, see Patent Literature 1).
In these organic-inorganic hybrid materials, a π-conjugated polymer can be evenly dispersed in an inorganic matrix. Based on this property, white-light emitting materials having excellent weather resistance have been proposed (for example, see Patent Literature 2).
Moreover, an organic-inorganic hybrid material containing an organic ligand, which is not easily prepared by the conventional sol-gel method, has been proposed by using metal oxides instead of inorganic oxides such as silica (for example, see Patent Literature 3).
Meanwhile, regarding a case where excellent light emitting efficiency is focused on, a luminescence hybrid material, which is obtained by combining clay mineral with a dye, or an electroluminescent element has been proposed (for example, see Patent Literature 4 and 5).
As described above, various light emitting materials have been examined so far. Particularly, light emitting hybrid materials having both the light emitting characteristics and weather resistance have been examined by using an organic material and an inorganic material in combination, and various proposals have been provided.